Electronic devices, such as smart phones, tablet computers, digital media players, and so forth, increasingly employ optical (e.g., light) sensors to control the manipulation of a variety of functions provided by the device. For example, optical sensors are commonly used by electronic devices to detect ambient lighting conditions in order to control the brightness of the device's display screen. Typical optical sensors employ photodetectors such as photodiodes, phototransistors, or the like, which convert received light into an electrical signal (e.g., a current or voltage).
Optical sensors are commonly used in gesture sensing devices. Gesture sensing devices enable the detection of physical movement (e.g., “gestures”) without the user actually touching the device within which the gesture sensing device resides. The detected movements can be subsequently used as input commands for the device. In implementations, the electronic device is programmed to recognize distinct non-contact hand motions, such as left-to-right, right-to-left, up-to-down, down-to-up, in-to-out, out-to-in, and so forth. Gesture sensing devices have found popular use in handheld electronic devices, such as tablet computing devices and smart phones, as well as other portable electronic devices, such as laptop computers, video game consoles, and so forth.
Optical sensors may also be utilized in bio-sensing and environmental sensing applications. For example, optical sensors can be used to sense blood pulse rates, blood oxygen rates, blood alcohol levels, and body or environmental temperature.